Impeller



June 27, 1939. 'w VAN RUSWUK 2,164,020

IMPELLER Filed Dec. 4. 1936 Patented June 27, 1939 UNITED STATES PATENT OFFICE Application December 4, 1936, Serial No. 114,195 In Germany December 12, 1935 2 Claims.

The present invention relates to the design of high speed impellers for high-speed turbo-blowers and pumps.

In blower and pump impeller-s of conventional 5 design the blades are fixed between an external cover disc on the one side and a hub disc on the other side, the hub disc being nxed to the driving shaft and having a sufficient diameter to serve also as a-` cover disc for the blades. The two cover discs for the blades are thus of different shape and correspondingly different stresses ocn cur in them. There is therefore always a difierence in the radial expansion of the two discs and the relative radial displacement of the external cover disc increases with the radial length of the cover discs used and may reach a very high value in the case of impellers having cover discs of large radial length. rIhe impeller blades may be fastened to the cover discs by a variety of means, such as by rivets, welding, etc. These fixing means have to transmit the centrifugal forces in the blades to the cover discs, and when there is a relative radial displacement of the cover discs the fixing means for the blades have 26 to bear an additional stress caused by the resistance of the said xing means to the aforementioned tendency for an unequal radial displacement of thecover discs to occur. These additional stresses increase with the radial length 30 of the cover discs and are extremely high when the impeller blades are disposed radially to the impeller axis. In the case of blowers with a high peripheral blade speed such as 1,000 feet per second or more, these'stresses can easily exceed the limit of safety.

It is an object of the present invention to provide a high speed impeller in which there is no difference in the radial deformation of both the impeller cover discs due to the centrifugal forces 40 occurring during rotation, so that the joints used for connecting the blades to the cover discs only have to withstand the centrifugal force of the blades.

It is the main object of the present invention to provide a high speed impeller comprising a plurality of concentric (coaxial) parts, one of which serves as the hub` part connecting the impeller with the shaft, and two other parts which are the cover discs for the bladed part of the impeller and expand in a similar manner and more than said hub disc when rotating at high speed, and to provide a connection between said hub disc and one of said cover discs which permits individual expansion of the bladed part independently of the hub disc and, at the same time deiinitely transmits the torque from the hub disc to the blades. The blades are arranged in between two cover discs of symmetrical configuration so that the stresses in the two discs are equal and there is no distortion of the impeller 5 or relative displacement between the cover discs even when they are of large radial length. Therefore, there are no undesired and excessive stresses on the joints between the blades and the cover discs. 10

Further and other objects of the present invention will be hereinafter set forth in the accompanying specification and claims and shown in the drawing, which by way of illustration, shows what I now consider to be a preferred em- 15 bodiment of my invention.

In the drawing:

Fig. 1 is a diagrammatic sectional View of a turbo blawer having an impeller according to my present invention. 20

Fig. 2 is a diagrammatic sectional view of a modified impeller according to the present invention.

Fig. 3 is a diagrammatic sectional View of another modication of the present invention. 25

Fig. 4 is a diagrammatic sectional view of yet another modication of the present invention.

Referring more particularly to Fig. l of the drawing, l is the driving shaft to which the hub disc 2 of the impeller is connected. Hub part 2 30 carries the cover disc 3 by means of an elastic ring 4 which is known per se. Cover disc 3 is of similar conguration as and symmetrically arranged to the external cover disc 5 and connected thereto by means of the impeller blades 6. At 35 increasing speed, cover disc 3 expands without causing undue stress on the hub disc 2 because of the elastic connection 4 between these parts. The symmetrical design of the bladed part of the impeller comprising parts 3, 5 and 6 assures that 40 there are no undesired stresses on blades 6 and particularly where they are connected to the cover discs 3 and 5, and furthermore it makes balancing of forces acting on said parts in axial direction possible because a gland l can be ar- 45 ranged on cover disc 3 on substantially the same diameter and as conveniently as gland 8 on cover disc 5. The pressures acting in axial direction on cover discs 3 and 5 are equal; due to the opening l2 provided on hub part 2, the same pressure, 50 namely, the suction pressure acts on both sides of said part so that all axial forces are well balanced.

The design of the impeller according to the present invention is suitable for the provision of 55 an additional impeller comprising hub disc 9 and blades l0 concentrically Within the main impeller comprising parts 2, 3, 4, 5 and 6. With such arrangement, the flow of the fluid is eiliciently diverted from the axial inlet direction to the radial direction through the main impeller.

As is shown in Fig. 2 of the drawing, instead of the elastic ring 4, pins ll which are of slightly conical configuration may be used for interconnecting the hub part 2 with the cover disc 3. At increasing speed, part 3 expands and radially glides on pins H which assure good centering of part 3 at all operating conditions and, at the same time, efficient transmission of torque.

If cylindrical bolts are used, these may either be fixed to part 2, as is shown in Fig. 3, or to part 3", as is shown in Fig. 4 of the drawing.

While I believe the above described embodiments of my invention to be preferred embodiments, I wish it to be understood that I do not desire to be limited to the exact details of design and construction shown and described, for obvious modifications will occur to a person skilled in the art.

I claim:

1. A high speed centrifugal pump comprising, in combination, a shaft, a high speed bladed impeller having blades whose radial length is at least several times the axial width and comprising two cover discs which together with the blades form an independent rotor element, the cross sectional conguration of one of said cover discs being substantially the reflected image of the cross sectional conliguration of the other of said cover discs, both said cover discs being arranged symmetrically with respect to the center plane of said impeller, a hub part connected to and rotated by said shaft, means movably connecting said hub part with one only of said cover discs for relative radial movement, whereby said connected cover disc can expand independently of said hub part and the torque is effectively transmitted from said hub part to said connected cover disc, and an additional, individual impeller situated concentrically and substantially Within said first-mentioned impeller and being also connected to and rotated by said shaft.

2. A centrifugal pump comprising, in combination, a shaft, a bladed impeller comprising two cover discs which together with the blades form an independent rotor element, the cross sectional configuration of one of said cover discs being substantially the reliected image of the cross sectional conguration of the other of said cover discs, a hub part connected to and rotated by said shaft, means movably connecting said hub part with one only of said cover discs for relative radial movement, whereby said connected cover disc can expand independently of said hub Dart and the torque is effectively transmitted from said hub part to said connected cover disc, and an additional, individual impeller situated concen trically and substantially within said first-mentioned impeller and being also connected to and rotated by said shaft.

WILLEM VAN RIJ SW IJ K. 

